So sorry for the long delay. I forgot I was gonna post pics to show difference between my old idler arm and new. This would have probably been more helpful if I would have compared them before putting the new one on vehicle.
Anywhoo, to late for that so hope this helps a least a little!
My replacement part is part #3350G(IDLER ARM, 1971-73 Mustang All, M/S & P/S) from California Mustang. However, I got the arm over 30 days ago. Both the price of the arm(I paid $43.95-free shipping, it's now $59.95) and the part picture have changed on the website. So side by side...looks like new arm isn't as angled as original.
Also nut on bottom is gone and has been replaced by the grease plug. Seems to work fine. I just took off the old, set the new in the same position, lined it up under the car and it fit in place easily. Tightened down and good to go. My engine is still not back so haven't driven it yet. I will have to post update later.
Okaaaay! that 73 stuff is different to 71's, BUT it is the geometry that matters more than the shape. Re-read my reply 2/04/16. As long as the radial distance, centerline to centerline, and the top of the drag link bushing is at the same height relative to the bottom bolt hole, then it matters not the angle of the arm is. The idler arm I used did have fitment issues with regard to the top bolt hole needing to be slotted, which I knew about. The US manufacturer screwed that up, but apart from that it is a quality part and has grease fittings on both swivels joints. I'm in the same boat here, until spring and I get my engine back, I can't test it either, but I don't anticipate any issues. I did get my power steering box rebuilt yesterday, so that's another job just sitting, waiting.
I'm sure you'll be ok with what you have. It's good to know that there are other options for replacement idler arms out there.
Geoff.